Using Google Earth in restoration ecology work
I haven't used Google Earth for several years so I don't know when enhancements have been made, but the current version has a fascinating "history" slider. For the area I was interested in (Black Earth Rettenmund Prairie), 7 different images were available: 4/1992, 4/2000, 9/2005, 9/2006, 9/2008, 11, 2010, and 10/2013. By clicking the slider arrow, you can seamlessly move from one date to the next. Since Kathie and I started managing restoration at BE Rettenmund in 2000, the work we have done passed before my eyes as I clicked the slider.
The best image is the newest (10/2013), which is shown here. As can be seen, the vegetation stands out clearly, and our trails and mowed fire break really show. Hopefully, a version of this image might be available that could be georeferenced in ArcGIS.
Black Earth Rettenmund is a fine remnant prairie, but at the time the Nature Conservancy purchased it (1986) it had seriously deteriorated. About half the 16 acre prairie and been overcome with trees and brush, including two major aspen clones and lots of sumac, gray dogwood, and honeysuckle. Despite frequent fire (mostly biennial), we are still fighting the legacy of those days. Note the location of the former aspen clone in the photo. The green there now is not aspen, but prairie willow and hazel (both native, but still invasive). Other areas of the preserve have patches of gray dogwood. Sumac was once an even worse scourge, but after our four years of heavy work, it is no longer a problem. See this link from my blog for details on how we dealt with sumac.